A numero numerum si sit tibi demere cura
Scribe figurarum series, vt in addicione.
Four things to know about subtraction: ¶ This is þe Chapter of subtraccioɳ, in the quych þou most know foure nessessary thynges. the first what is subtraccioɳ. þe secunde is how mony nombers þou most haue to subtraccioɳ, the thryd is how mony maners of cases þere may happe in þis craft of subtraccioɳ. The fourte is qwat is þe profet of þis craft. ¶ As for the first; þe first, þou most know þat subtraccioɳ is drawynge of one nowmber oute of anoþer nomber. the second; As for þe secunde, þou most knowe þat þou most haue two rewes of figuris one vnder anoþer, as þou [addyst] in addicioɳ. the third; As for þe thryd, þou moyst know þat foure maner of diuerse casis mai happe in þis craft. the fourth. ¶ As for þe fourt, þou most know þat þe profet of þis craft is whenne þou hasse taken þe lasse nomber out of þe more to telle what þere [leues] ouer þat. & þou most be-gynne to wyrch in þis craft in þe ryght side of þe boke, as þou diddyst in addicioɳ. Versus.
¶ Maiori numero numerum suppone minorem,
¶ Siue pari numero supponatur numerus par.
leaf 143 a. * ¶ Here he telles þat Put the greater number above the less. þe hier nomber most be more þen þe neþer, or els eueɳ as mych. but he may not be lasse. And þe case is þis, þou schalt drawe þe neþer nomber out of þe hyer, & þou mayst not do þat yf þe hier nomber were lasse þan þat. ffor þou mayst not draw sex out of 2. But þou mast draw 2 out of sex. And þou maiste draw twene out of twene, for þou schal leue noȝt of þe hier twene vnde versus.
The Cases of the Craft of Subtraction.
¶ Postea si possis a prima subtrahe primam
Scribens quod remanet.
The first case of subtraction. Here is þe first case put of subtraccioɳ, & he says þou schalt begynne in þe ryght side, & draw þe first figure of þe neþer rewe out of þe first figure of þe hier rewe. qwether þe hier figure be more þen þe neþer, or eueɳ as mych. And þat is notified in þe vers when he says “Si possis.” Whan þou has þus ydo, do away þe hiest figure & sett þere þat [leues] of þe subtraccioɳ, Here is an example. lo an Ensampulle 234
122 draw 2 out of 4. þan leues 2. do away 4 & write þere 2, & latte þe neþer figure stonde stille, & so go [for-by] oþer figuris till þou come to þe ende, þan hast þou do.